Python’s integer (int) type

3 min readApr 15, 2022

Python uses int to represent integers (or whole numbers) such as 10, 100, or -30.

Create an integer

We can create an int variable through an assignment with an integer literal, for example

x = 5
print(x)5type(x)int

We can also create an int variable through an assignment with an expression that produces an integer. Here are some examples of expressions producing integers.

# Addition of integers
x = 5 + 10
print(x)
print(type(x))15
<class 'int'># Multiplication of integers
x = 5 * 10
print(x)
print(type(x))50
<class 'int'>

Integers in Python can be arbitrarily long (there is no overflow behavior as in some other languages).

# A very long int
x = 3565622255488771132323355767676856586585965999884384
print(x)
print(type(x))3565622255488771132323355767676856586585965999884384
<class 'int'>

When use int?

We use int for values that should be integers such as age, years, number of children, etc.

Typecasting

Similar to what we have learned with bool, we use int() function to convert values from other types to int. However, not all values can be converted to int (only integer-like values can).

Example 1: values that can be converted to int

From bool

# True becomes 1
int(True)1# False becomes 0
int(False)0

From float

# Decimal part is truncated
int(12.34)12

From str

# Strings that look like an integer
x = int("10")
print(x)
print(type(x))10
<class 'int'># White spaces at two ends are ignored
x = int("  -10 ")
print(x)
print(type(x))-10
<class 'int'># Leading zeros are also ignored
x = int("  -00010 ")
print(x)
print(type(x))-10
<class 'int'>

Operations on int

Arithmetic operations

Addition, subtraction, multiplication

print(2 + 3)
print(2 - 3)
print(2 * 3)5
-1
6

Real division (return real numbers, or float)

2 / 30.6666666666666666# Even 4 is divisible by 2
# We still get a float back
4 / 22.0

Integer division (get the quotient)

2 // 30

Modulus (get the remainder)

2 % 32

Exponential

2**38

Negation

-10-10x = 10
print(-x)-10

Note that a bool is actually an integer under the hood with True and False equivalent to 1 and 0.

Let’s confirm this.

# Same value
print(True == 1)
print(False == 0)True
True# Use isinstance
print(isinstance(True, int))
print(isinstance(False, int))True
True

Thus, we can perform arithmetic on bool and int, and the result is promoted to type int (more general)

# Bool plus bool
x = True + True
print(x)
print(type(x))2
<class 'int'># Int plus bool
x = 5 + True
print(x)
print(type(x))6
<class 'int'>

Comparision operations

Comparisons on numbers (int or float) always return a bool. (Already covered in the previous article)

However, strings like "1,000,000" (contains ,) or "12.34" are not valid. Try them yourself to see errors.

Practice

Ex 1

Do the following

Create a variable x with value 100
Show its value and type

Ex 2